1. Technical Field
This invention generally relates to windows having muntin bars that simulate the appearance of traditional divided lite windows having individual panes of glass set in wooden muntin bars. More particularly, the present invention relates to a method of fabricating muntin bars on automated machinery for use in simulated divided lite windows. Specifically, the present invention relates to a method of automatically sizing, cutting, and joining foam strips to the top and bottom edges of traditional thin metal inner muntin grid elements for use in insulating windows having outer muntin bars positioned in coincidental alignment with the inner muntin bars. The invention also relates to the structure of the muntin bars.
2. Background Information
Traditional windows have individual panes of glass separated by wooden muntins. While these windows are attractive and have functioned for many years, they are relatively expensive to fabricate. The expense is particularly high when a consumer desires an insulating window having spaced panes of glass sealed together by a perimeter spacer. A single window having twelve panes of glass requires twelve spacers, twenty-four panes of glass, and a precisely formed muntin grid. In addition to the cost of materials, the assembly process is also relatively expensive. Thus, although consumers desire the aesthetic properties of traditional divided lite windows, most are unwilling to pay for a true divided lite window.
Modern, energy efficient insulating windows include at least two panes of glass separated by a spacer to form a sealed cavity that provides insulating properties. These insulating windows are most efficiently manufactured with two large panes of glass separated by a single spacer disposed at the perimeter of the panes. Various solutions have been implemented to provide the divided lite appearance in insulating windows. One solution to the problem has been to place a muntin bar grid between the panes of glass. Another solution has been to place the muntin bar grid on the outer surface of one, or both, panes of glass. Although these solutions provide options for consumers, each has visual drawbacks when compared with traditional muntin bars.
Placing muntin bar grids between the panes of glass is one of the most common solutions to the divided lite problem. In fact, so many internal muntin grids are fabricated that automated muntin bar manufacturing equipment has been created and is used in the art. This equipment works in cooperation with the automated window manufacturing equipment. In this equipment, the user inputs the desired size of window and the computer automatically selects the ideal number of grid intersections to form an aesthetically pleasing muntin bar grid. In other embodiments, the user may override the automatic selection and manually select the number of muntin bar intersections in the grid. The computer then controls automated fabricating equipment that roll forms flat metal stock into the hollow, substantially rectangular muntin bars used to form the muntin bar grid. The muntin bars are dadoed or notched at their intersections half-way through their thickness to provide the overlapping joint required to form the grid. These notched areas are also automatically formed. The muntin bars are then cut to length and an assembler manually assembles the bars into a grid that is mounted to the spacer that spaces the inner and outer panes of glass. The muntin bar grid is attached to the spacer with specially designed clips that fit into holes punched into the spacer during the manufacture of the spacer. These systems allow muntin bar grids to be quickly and easily manufactured for a relatively low price after the user invests in the automated equipment. The muntin bar grids are painted and deburred to have a pleasing appearance either before or after the grid is assembled.
One product developed by Edgetech I. G. of Cambridge, Ohio, in response to the insulating window muntin bar problem includes the use of a pair of material strips positioned on the upper and lower edges of metal muntin bars inside an insulating window assembly. Outer muntin bars are then provided in coincidental alignment with the inner muntin bars to achieve a simulated divided lite appearance. The material strips visually join the aligned outer muntin bars to create the appearance that the muntin bar grid extends entirely through the insulated window assembly. This product also hides the metal muntin bars. The metal muntin bars thus do not have to be painted and may be fabricated from a lower quality material than exposed, painted inner metal muntin bars. Although this product achieved acceptance by the consumer because of its visual appearance, the insulating window manufacturers objected to the relatively large amount of labor required to size, cut, and install the material strips. It is thus desired in the art to provide a method for sizing, cutting, and installing the material strips to muntin bars that are fabricated with automated machinery.
Another problem encountered with this product occurs when the material strips are stretched during installation or applied to the outside of a curved muntin. It has been found that the strips relax overtime and delaminate causing the window to have an unattractive appearance. It is desired in the art to provide a solution to this delamination problem.